Thermal Vacuum Valve

Mounted on intake manifold, thermal vacuum valve is connected between vacuum port in carburetor and EGR valve. Valve opens when coolant temperature reaches 115-129°F (46-54°C) on I-Mark and P'UP and 97-111°F (36-44°C) on Impulse models. With valve closed, EGR system does not operate. As coolant warms, valve opens allowing normal EGR operation.